I use Firefox (LibreWolf with Mozilla sync) on multiple devices. To have my tabs, extensions and history easy available I use Mozilla for syncing that data.
Would it be possible to just use a generic sync service like rsync or something, to sync the profile folders and every file in it?
Or would that break or corrupt data?
I’d suggest weekly system image backups and daily differential/incrementals. A couple of minutes a day saves everything (and you will sleep soundly)